Any type of powered mechanical apparatus will, in general, be subjected to load conditions or requirements that will vary from time to time. When the load increases the machine must either increase its available supply of power or else must slow its operation, and when the load decreases the opposite response occurs.
There is often a great deal of difference in the conditions for starting the operation of a powered machine, and for merely continuing to run it once it has been started. Many types of gear shifts and variable speed transmissions have been provided for starting up a load at a lower speed than its ultimate running condition.
The present invention is concerned, however, with changes in running conditions rather than with start-up. As one example, a powered vehicle strikes an obstruction upon a roadway surface which temporarily requires a great increase in the driving power applied to one or more wheels in order to overcome the obstruction. And in industrial plants where rotary power is being transmitted, a very sudden load change may cause damage to the power transmission apparatus unless adequate means are provided for accommodating to the change.
The object of the present invention, therefore, is to provide a new and improved mechanism for transmitting rotary power, and which has a unique capability for responding to sudden changes in the mechanical load placed upon it.
A more specific object of the present invention is to provide power transmission apparatus as aforesaid, which is particularly well adapted for use in a wheeled vehicle.